The invention relates to a poly valve system for internal combustion engines having non-parallel valve placement. More particularly, the invention relates to a valve system which employs several independently operated intake valves and several independently operated exhaust valves per cylinder so that non-parallel valve arrangements can be achieved to maximize engine performance.
In an internal combustion engine, intake and exhaust valves serve a crucial function. They must each open at an appropriate time to allow combustible gases in or exhaust out, and remain tightly closed at all other times to maximize the power derived from combustion.
The performance of the engine is also closely linked to the valves. It is well known that the more an engine xe2x80x9cbreathesxe2x80x9d the more power it will generate. This is known as xe2x80x9cvolumetric efficiencyxe2x80x9d. It seems obvious that the more fuel and air that enters the combustion chamber, the greater the force of the explosion and the greater the power generated thereby. However, the ability of the engine to eliminate combustion by-products is also an important factor in performance. In fact the peak horsepowerxe2x80x94the practical rev limit for an enginexe2x80x94is in large part determined by the speed at which the exhaust valves can no longer expel sufficient burned gases to allow efficient combustion to occur.
Traditionally, valve systems are fully mechanical systems. At least one cam shaft is used to precisely determine the times during the engine cycle when each valve is to be opened and closed. For each valve, a cam follower traces the movements of the cam shaft, and causes the valve xe2x80x9cpoppetxe2x80x9d to open and close. One problem with this arrangement is the lack of flexibility. Once the cams are set, it is not possible to change the relative opening and closing times of the valves. In addition, the entire cam system itself comprises numerous moving parts which require maintenance and which to some extent detract power from the engine.
Over the last two decades, adding an extra intake and an extra exhaust valve per cylinder has become prevalent in automobile engines of all types. This change has thus lead to increased engine performance by simply increasing the inward and outward flow of the combustion chamber, and thus increasing the volumetric efficiency. In such engines, it has been the general practice to have both intake valves to open and close at the same time.
Experimentation with increasing the number of valves has revealed practical limitations. Having a large number of valves quickly increases the complexity of the cylinder head configuration, and causes porting problems. Some have sought to maximize the number of valves by conceiving variations of traditional cam operated valve technology.
Further, in a multi-valve system it would be desirable to orient the valves toward the cylinder center line. However, traditional valve operating technology the limits valve angle within the cylinder head, such that valves must be parallel to operate from the same cam shaft. Unfortunately, the use of non-parallel valves would help maximize engine performance.
The most thermally efficient chamber has a hemispherical chamber xe2x80x9croofxe2x80x9d. Unfortunately with the limitations for valve placement discussed above, only one intake and one exhaust valve could be used with a hemispherical chamber. In particular, using existing technology, duplicative valves must remain parallel. Parallel valves will not work with a hemispherical chamber using traditional valve operating technology. Thus in a thermally efficient hemispherical chamber, volumetric efficiency cannot be optimized.
In one early attempt, following World War II, an AJS motorcycle known as xe2x80x9cthe porcupinexe2x80x9d attempted to use two non-parallel intake valves and two non-parallel exhaust valves. This design failed miserably because the use of conventional cam-based opening technology was unsuitable for reliably opening non-parallel valves.
U.S. Pat. No. 5,375,568 to Manolis et al. discloses a multi-valve internal combustion engine which has a cluster valve system, wherein four intake valves are mechanically ganged and all operate off a common cam follower. Four exhaust valves are also provided in a similar arrangement.
U.S. Pat. No. 5,111,791 to Onodera discloses a cylinder head and valve train arrangement for a multiple valve engine. Onodera discloses a six valve arrangement, wherein special attention has been given to solving the problem of positioning and synchronizing cam shafts to operate these valves. Care is taken to carefully synchronize the opening of all four intake valves even though two separate cam shafts are used for opening these valves.
U.S. Pat. No. 4,658,780 to Hosoi; U.S. Pat. No. 5,007,387 to Arao; U.S. Pat. No. 5,094,197 to Rosa; and U.S. Pat. No. 5,184,580 to Ascari all disclose multiple intake and exhaust valve systems. These patent references are all concerned with working out the mechanics of a multi-valve system using existing cam operated valves. They are generally concerned with synchronizing the valves where the use of multiple valves conflicts with the ordinary design constraints of standard single cam valve operation.
U.S. Pat. No. 4,587,936 to Matsuura et al. discloses a valve control system which employs traditional cam-based valve opening. Matsuura has provisions to mechanically deactivate one of the intake valves under certain engine conditions. However Matsuura is not able to provide any other flexibility or control over valve opening or timing, other than being able to simply disable one of the valves.
U.S. Pat. No. 5,669,341 to Ushirono et al. discloses a valve operating system which uses an electrically operated valve in addition to a mechanically operated valve. However, Ushirono et al. only employs the electrically operated valve during certain engine conditions.
While these units may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present invention as disclosed hereafter. In particular, these multiple valve systems all seek to employ a modified mechanical cam-based opening system. They are generally concerned with ensuring that all intake valves open together. However, some study has revealed that carefully creating turbulence in the combustion chamber can increase engine performance. But, the prior art systems are unsuitable for experimentation to optimize such effects, because they do not allow independent operation or opening timing between the various intake valves. In addition, internal stresses generated by the cam system inertia in itself limits rev speeds that the engine can achieve. Further because they employ traditional valve opening technology, they cannot take advantage of the freedom on non-parallel valve positioning.
It is a primary object of the invention to simultaneously maximize both thermal and volumetric efficiency. Accordingly, the invention seeks to allow multiple intake and exhaust valves in a hemispherical chamber design. Thus, the independent valve technology of the present invention allows non-parallel valve placement within a hemispherical chamber.
It is an object of the invention to increase the performance of an internal combustion engine. Accordingly, the invention is a poly valve system which employs several intake and several exhaust valves per cylinder.
It is another object of the invention to provide multiple valves per cylinder without requiring a complex cylinder head configuration. Accordingly, the poly valve system eliminates the cam structure ordinarily required in four stroke engines.
It is yet another object of the invention to create turbulence within the cylinder during the intake cycle. Accordingly, fully independent valve operation and freedom of valve placement allow the effects of intake turbulence to be optimized.
It is a further object of the invention to greatly increase the revolution limit of the engine. Accordingly, the use of multiple valves, and the lack of reliance on a mechanical system to open and close the valves greatly increases the allowable rotary speed for the engine. In addition, the lower mass and complexity of the poly valve system allows greater speeds to be achieved.
It is a still further object of the invention that practically random valve operation is achievable. Accordingly, electric, hydraulic, or pneumatic valves may be employed so that fully random selection of opening and closing times can be determined and executed in accordance with achieving maximum efficiency.
It is yet a further object of the invention to reduce the overall size of the engine. Accordingly, by eliminating standard camming mechanisms, a significant space savings can be achieved.
It is a still further object of the invention to optimize the shape of the combustion chamber. Accordingly, by having the ability to place numerous, smaller valves at flexible locations in the cylinder head, the piston need not be altered to provide valve clearance and thus can have a smoother shape.
The invention is a poly valve system for an internal combustion engine having at least one cylinder having a bore and a cylinder center line, a piston capable of reciprocal travel within the bore, a cylinder head adjacent the bore having a hemispherical cylinder roof, intake and exhaust manifolds, and a combustion chamber defined between the cylinder head and the piston, comprising a plurality of independently operated valves. Valve seats comprise openings in the cylinder head between one of the manifolds and the combustion chamber. Poppet valves are situated in the valve seats to selectively allow communication between one of the manifolds and the combustion chamber. The valves are independently operable by a control signal, may be non-parallel, and may be substantially oriented toward the cylinder center line.